Agudelo E, Sperling J, Costanzo L S, Bellini M, Zavatta A, Vogel W
AG Theoretische Quantenoptik, Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
Phys Rev Lett. 2017 Sep 22;119(12):120403. doi: 10.1103/PhysRevLett.119.120403. Epub 2017 Sep 21.
We derive and implement a general method to characterize the nonclassicality in compound discrete- and continuous-variable systems. For this purpose, we introduce the operational notion of conditional hybrid nonclassicality which relates to the ability to produce a nonclassical continuous-variable state by projecting onto a general superposition of discrete-variable subsystem. We discuss the importance of this form of quantumness in connection with interfaces for quantum communication. To verify the conditional hybrid nonclassicality, a matrix version of a nonclassicality quasiprobability is derived and its sampling approach is formulated. We experimentally generate an entangled, hybrid Schrödinger cat state, using a coherent photon-addition process acting on two temporal modes, and we directly sample its nonclassicality quasiprobability matrix. The introduced conditional quantum effects are certified with high statistical significance.
我们推导并实现了一种用于刻画复合离散和连续变量系统中非经典性的通用方法。为此，我们引入了条件混合非经典性的操作概念，它与通过投影到离散变量子系统的一般叠加态来产生非经典连续变量态的能力相关。我们讨论了这种量子形式在量子通信接口方面的重要性。为了验证条件混合非经典性，我们推导了非经典性准概率的矩阵形式并制定了其采样方法。我们通过对两个时间模式作用相干光子添加过程，实验生成了一个纠缠的混合薛定谔猫态，并直接对其非经典性准概率矩阵进行采样。所引入的条件量子效应具有很高的统计显著性。
